Vertebral discs separate adjacent vertebral bodies and allow for relative movement between the adjacent vertebral bodies. Disease, trauma and the like, can cause deterioration of these natural discs, eventually requiring removal of the diseased or damaged disc. In certain circumstances, the disc is removed and the adjoining vertebral bodies fused. Alternately, the natural disc can be replaced with a prosthetic disc.
There are a wide variety of prosthetic discs. Many of these use a ball joint type mechanism, such as disclosed in Buttner-Janz et al., U.S. Pat. No. 5,401,269 and Diaz et al., U.S. Pat. No. 7,083,651. Other replacement discs are disclosed in Navarro et al., U.S. Pat. No. 5,534,030 and Patil, U.S. Pat. No. 4,309,777, and Bartish, Jr., et al., U.S. Published application No. 2006/0004453. Such devices may suffer from a variety of different problems such as excessive height, lack of resistance to bending, fixed axes of rotation, wear debris, and revision complications and risks.
Accordingly, there is a need for an improved prosthetic disc that overcomes these problems associated with known prosthetic discs.